Solar cell having a pn hetero-junction

Abstract

Disclosed herein is a solar cell, which includes a first conductive layer, a photoelectric conversion layer and a second conductive layer. The photoelectric conversion layer is disposed above the first conductive layer. The photoelectric conversion layer includes a silicon substrate and a CIGS layer that is in contact with the silicon substrate, so that a PN hetero-junction is formed between the silicon substrate and the CIGS layer. The second conductive layer is disposed above the photoelectric conversion layer.

1 . A solar cell, comprising:
 a first conductive layer;   a photoelectric conversion layer for converting light into electricity, the photoelectric conversion layer being disposed above the first conductive layer, wherein the photoelectric conversion layer comprises a silicon substrate and a copper indium gallium selenide layer in contact with the silicon substrate, and the copper indium gallium selenide layer forms a PN hetero-junction with the silicon substrate, wherein the copper indium gallium selenide layer has a gallium concentration distribution, and a gallium concentration at an end position adjacent to the PN hetero junction is less than a gallium concentration at another end position opposite to the PN hetero-junction; and   a second conductive layer disposed above the photoelectric conversion layer, wherein the first conductive layer and the second conductive layer are configured to transmit the electricity.   
     
     
         2 . The solar cell according to  claim 1 , wherein the first conductive layer and the second conductive layer are respectively a metal layer and a transparent conductive layer, and the copper indium gallium selenide layer is positioned between the transparent conductive layer and the silicon substrate. 
     
     
         3 . The solar cell according to  claim 1 , wherein the copper indium gallium selenide layer comprises P-type copper indium gallium selenide, and the silicon substrate comprises a N-type silicon substrate. 
     
     
         4 . The solar cell according to  claim 3 , wherein the silicon substrate comprises a heavily doped N+ region positioned on a surface adjacent to the first conductive layer. 
     
     
         5 . The solar cell according to  claim 1 , wherein the photoelectric conversion layer does not comprise cadmium sulfide. 
     
     
         6 . The solar cell according to  claim 1 , wherein the copper indium gallium selenide layer comprises N-type copper indium gallium selenide, and the silicon substrate comprises a P-type silicon substrate. 
     
     
         7 . The solar cell according to  claim 6 , wherein the silicon substrate comprises a heavily doped P+ region positioned on a surface adjacent to the first conductive layer. 
     
     
         8 . (canceled) 
     
     
         9 . The solar cell according to  claim 1 , wherein the copper indium gallium selenide layer has a thickness of about 0.1 μm to about 5 μm. 
     
     
         10 . The solar cell according to  claim 1 , wherein the first conductive layer and the second conductive layer are respectively a metal layer and a transparent conductive layer, and the copper indium gallium selenide layer is positioned between the metal layer and the silicon substrate. 
     
     
         11 . The solar cell according to  claim 1 , wherein the copper indium gallium selenide layer has an atomic ratio of gallium over the sum of gallium and indium of about 0.2 to about 0.9. 
     
     
         12 . The solar cell according to  claim 1 , wherein the copper indium gallium selenide layer has a thickness less than a thickness of the silicon substrate. 
     
     
         13 . The solar cell according to  claim 1 , further comprising a reflecting layer disposed between the silicon substrate and the first conductive layer. 
     
     
         14 . The solar cell according to  claim 13 , wherein the reflecting layer comprises a conductive oxide selected from a group consisting of indium tin oxide, indium tungsten oxide, zinc oxide doped with aluminum, and zinc oxide doped with gallium. 
     
     
         15 . The solar cell according to  claim 13 , wherein the reflecting layer is made of a non-conductive material, and the reflecting layer has a plurality of contact holes for electrically connecting the first conductive layer to the photoelectric conversion layer. 
     
     
         16 . The solar cell according to  claim 1 , wherein the silicon substrate is in contact with the first conductive layer. 
     
     
         17 . The solar cell according to  claim 1 , wherein the silicon substrate is in contact with the second conductive layer. 
     
     
         18 . The solar cell according to  claim 1 , wherein the copper indium gallium selenide layer is in contact with first conductive layer. 
     
     
         19 . The solar cell according to  claim 1 , wherein the copper indium gallium selenide layer is in contact with second conductive layer. 
     
     
         20 . The solar cell according to  claim 1 , wherein the copper indium gallium selenide layer has a thickness of about 0.1 μm to about 1 μm. 
     
     
         21 . A solar cell, comprising:
 a first conductive layer;   a photoelectric conversion layer for converting light into electricity, the photoelectric conversion layer being disposed above the first conductive layer, wherein the photoelectric conversion layer comprises a silicon substrate and a copper indium gallium selenide layer in contact with the silicon substrate, and the copper indium gallium selenide layer forms a PN hetero-junction with the silicon substrate, wherein the copper indium gallium selenide layer has a atomic ratio of gallium over the sum of gallium and indium of about 0.2 to about 0.9; and   a second conductive layer disposed above the photoelectric conversion layer, wherein the first conductive layer and the second conductive layer are configured to transmit the electricity.